Abstract WP340: Impact of Increasing Primary Stroke Center Transfers on Comprehensive Stroke Center Capacity

Introduction: Given the time-sensitive benefits of acute stroke (AS) treatments, stroke systems of care must balance reducing door-in-door-out (DIDO) time at primary stroke centers (PSCs) with capacity limits at comprehensive stroke centers (CSCs). For example transferring more AS patients earlier in the process (e.g., prior vascular imaging for large vessel occlusion) from PSCs would result in more inappropriate transfers to CSCs that could overburden these centers.We conducted a simulation to estimate the balance between increased AS transfers from PSCs to CSCs and the percent of CSC time on “bypass” (inability to accept transfers to neuro-ICU). Methods: Clinicians from 3 Chicago-area CSCs and 3 affiliated PSCs and the Chicago Emergency Medical Services (EMS) created a PSC DIDO process map. We assumed CSC time on bypass is affected by AS and non-AS admissions from the CSC and from the affiliated PSCs. Input data were obtained fromtheChicago region registry (e.g., # PSC to CSC transfers), peer reviewed literature (US average transfer rate of AS patients to CSCs), EMS (PSC-CSC affiliations), and CSCs (e.g., average bed occupancy rates). CSC size was estimated by #neuro-ICU beds: small (12 beds), medium (23 beds), and large (28 beds). The simulation output was % time of CSC on “bypass”. Results: Table shows % time of CSC on bypass by varying PSC AS transfer rates for each category of CSC size. Larger increases in PSC transfer rates resulted in modest increases in CSC bypass rates, particularly for medium and large CSCs. Validation with data from one CSC showed < 4% overestimate of CSC % time on bypass. Conclusion: CSCs with more beds have efficiencies of scale leading to lower % time on bypass, even with increases in PSC AS transfer rates proportionate to CSC size. This model allows stroke systems of care to compute regional CSCs’ % time on bypass based on actual PSCs’ transfer rates and CSC size.